Referring to FIGS. 5A and 5B, a laser robot in general using a high-energy laser beam requires flexible pipes 7a for conveying a liquid coolant so as to cool reflecting mirrors 6 which are arranged to deflect the laser beam and a flexible pipe 7b for conveying an inert gas serving as an assist gas in laser machining. The flexible pipes 7a and 7b are arranged around a robot wrist 4 holding a laser beam projecting device 5 thereon These flexible pipes 7a and 7b are sufficiently slack so that the flexible pipes 7a and 7b are able to absorb the twisting and pulling that act thereon when the movable components of the laser robot, including the robot body, the robot upper arm, which are not shown, the robot forearm 3 and the robot wrist 4, operate according to their respective degree of freedom of movement.
However, problems arise when the flexible pipes 7a and 7b are arranged slackly around the robot wrist 4, namely, it is possible that the flexible pipes 7a and 7b will interfere with peripheral equipment or other equipment when the laser robot performs an operation including laser machining, and the flexible pipes may be damaged or broken by debris and welding spatters from the workpiece during a laser welding operation or laser cutting operation.
If the pipes are extended in a sheathing pipe of the robot wrist so as to improve the piping arrangement, the robot wrist must be provided with a sheathing pipe of increased diameter, which conflicts with functional requirements suggesting that a robot working end must be formed in the smallest and the lightest possible construction. Furthermore, when the pipes extend in the sheathing pipe of the robot wrist, the liquid coolant will flow into the mechanism of the robot wrist if the liquid coolant leaks from the pipes. Thus, using a sheathing pipe for protecting the flexible pipes is not yet practical.